Treatment of artificial material



Patented Apr. 30, 1935 PATENT or FiCE TREATMENT OF ARTIFICIAL MATERIAL William Alexander Dickie and Percy Frederick Combo Sowter, Spend assignors to 'Celanese on, near Derby, England, Corporation of America,

a corporation of Delaware rial No. 399,384. 'In 5, 1928 13 Claims.

This invention relates to the treatment of filaments, threads, ribbons, films or other products consisting of or containing cellulose derivatives, for example cellulose acetate, formate, propionate, butyrate, or other carboxylic acid or other esters of cellulose, or methyl, ethylor benzyl cellulose or other cellulose others.

In Patent No. 1,465,994 processes are described for the manufacture of filaments, threads or films from solutions of cellulose acetate by co.- agulation in baths containing thiocyanates. During the process of the formation of the fila ment, thread or film a certain quantity of the thiocyanate finds its way into the product, and for various reasons its removal is very desirable. A simple washing with water alone'has a dele- "terious action upon the lustre and strength or" the products. Similarly Zinc chloride and other water-soluble substances which may be used in the precipitating baths (see prior specification No. 1,467,493) may have a detrimental effect if retained in the filaments, threads or films, and may result in decreased lustre and strength if it attempted to remove them by washing with water alone.

The object of the present invention is to remove such substances from the formed filaments, threads, filmsfor other products, whether these be made of cellulose acetate or other cellulose derivatives, without impairing the lustre or strength of tl e materials. The processes of the presontinvention may even result in an increase in lustre and/or strength of the products.

By the resent invention the removal of such substances from the filaments, threads, ribbons, films or other materials is effected by treatment with aqueous solutions of substances which either prevent the delustering action of hot or boiling aqueous media or which are capable of restoring or imparting lustre to partially or entirely delustred products;

Such substances are in general salts, and preferable normal salts, sugars and substances which are solvents or swelling agents for the cellulose derivative. Particular examples which we have found especially useful are sodium chloride or acetate, potassium chloride or sulphate, ammonium chloride or sulphate, diacetone alcohol, diethyl tartrate, ethyl lactate and the acetins, e. g. triacetin,

The washing with the solution of the desired agent may be effected in any desired manner, for example the washing solution may be applied as an auxiliary bath after the coagulating bath or it may be introduced into the feed funnel of a Drawing. Application October 12, 1929, Se-

Great Britain November (Cl. l854) centrifugal box used to wind up the formed filamerits or threads, or it may be applied tothe products after winding, for example when they.

are in 'hank or bobbin form. The washing operation with solutions of salts, for example 10% solution of ammonium sulphateor sodium chloride or acetate, is preferably followed by simple water washing. In the case of washing with solutions of solvents or latent solvents, for example with a 5 to 50% aqueous solution of diacetone alcohol, a subsequent water washing is not necessary: in fact it is preferable to use two or more washing solutions of decreasing concentration.

It is found that of the solvents or latent solvents which are suitable for the purpose of the present invention those which have a higher boiling point or lower volatility than water are preferable in that their use results in a higher lustre and greater strength in the product, particularly if they are allowed to dry in the products.

For the purpose of effecting economy inthe use of solvents in the above described washing operations, it may be convenient to apply first of all, for the purpose of removing the ammonium thiocyanate or the like, a saline wash liquor and to follow it by a wash liquor containing a solvent for the cellulose derivative.

The following examples illustrate the invention but are not to be considered as limiting it in any way:-

Example 1 Example 2 A thread spun as in Example '1 into a 15% aqueous ammonium thiocyanate solution is run on to perforated bobbins, on which it is washed by means of an aqueous solution of ammonium sulphate, the concentration of which is gradually reduced during the washing operation. The concentration of the initial wash liquor may for example be 10% and preferably the concentration is reduced until water alone is finally em ployed. The wash liquor may for instance be applied in the form of a steady spray.

Instead of sodium chloride or ammonium sulphate used in Examples 1 and 2, other salts, for instance those listed above in the general description, may be employed.

Example 3 A thread spun as in Example 1 into a 15% aqueous ammonium thiocyanate solution is hanked or run on to bobbins. The hanks or bobbins are immersed in a 10% aqueous solution of diacetone alcohol until the thread. is free from thiocyanate. The excess of diacetone alcohol is then removed, for example by shaking. squeezing or centrifuging, and the residue is allowed to dry in.

In a similar manner other solvents for t e cellulose derivative may be applied for the purpose of washing, for instance the acetins, diethyl tartrate or ethyl lactate.

Again, thiooyanate, zinc chloride or other water-soluble substances which may have a detrimental eiTect may be removed by the above methods from threads, ribbons, films, etc. of other cellulose esters or ethers. Furthermore the products may, if desired be treated after they have been twisted or otherwise associated with other fibres.

What we claim and desire to secure by Letters Patent isz- 1. In the treatment with aqueous media of materials containing cellulose derivatives which contain soluble salts, the step of preventing delustring of said materials by shooting treatment in the presence of dilute solutions of water soluble substances selected from the group consisting of solvents and swelling agents capable of imparting lustre to cellulose derivatives delustred by the action of hot aqueous media.

2. In the treatment with aqueous media of materials containing cellulose acetates which contain soluble salts, the step of preventing delustring of said materials by effecting treatment in the presence of dilute solutions of water soluble substances selected from the group consisting of solvents and swelling agents capable of imparting lustre to cellulose acetate delustred by the action of hot aqueous media.

3. In the treatment with aqueous media of materials containing cellulose acetates which contain thiocyanates, the step of preventing delustring of said materials by eiiecting treatment in the presence of dilute solutions of Water soluble substances selected from the group consisting of solvents and swelling agents capable of imparting lustre to cellulose acetate delustred by the action of hot aqueous media. n 4. In the treatment with aqueous media of materials containing cellulose acetates which contain zinc chloride, the step of preventing delustring of said materials by effecting treatment in the presence of dilute solutions of water soluble substances selected from the group consisting of solvents and swelling agents capable of imparting lustre to cellulose acetate delustred by the action of hot aqueous media.

5. Process for the treatment of materials containing cellulose acetates which contain soluble salts, so as to remove said salts without delustring, comprising treating said materials with dilute aqueous solutions of swelling agents for the cellulose acetate.

6. Process for the treatment of materials containing cellulose acetates which contain soluble salts, so as to remove said salts without delustring, comprising treating said materials with dilute aqueous solutions of swelling agents for the cellulose acetate of higher boiling point than water.

7. Process for the treatment of materials containing-cellulose acetates which contain soluble salts, so as to remove said salts without delustring, comprising treating said materials with aqueous solutions of organic swelling agents for the cellulose acetate.

8. Process for the removal of water-soluble salts from materials containing cellulose derivatives comprising treating said materials with an aqueous solution of a substance selected from the group consisting of solvents and swellingagents capable of imparting inherent lustre to cellulose derivatives delustered by the action of hot aqueous media.

9. Process for the removal of water-soluble salts from materials containing cellulose acetate comprising treating said materials with an aqueous solution or" a substance selected from the group consisting of solvents and swelling agents capable of imparting'inherent lustre to cellulose acetate delustered by the action of hot aqueous media.

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10. Process for the removal of water-soluble salts from materials containing cellulose derivatives comprising treating cellulose derivative materials containing such water-soluble salts with an aqueous solution of a substance selected from the group consisting of solvents and swelling agents for the cellulose derivative capable of imparting lustre to cellulose derivatives delustered by the action of hot aqueous media, said solution being unsaturated with respect to the salt to be removed.

11. Process for the removal of water-soluble salts from materials containing cellulose acetate H comprising treatingcellulose acetate materials containing such water-soluble salts with an aqueous solution of a substance selected from the group consisting of solvents and swelling agents for the cellulose acetate capable of imparting lustre to cellulose acetate delustered by the action of hot aqueous media, said solution being unsaturated with respect to the salt to be removed.

12. Process for the treatment of materials containing cellulose derivatives which contain soluble salts, so as to remove said salts without delustering, comprising treating said materials with aqueous solutions of swelling agents for the cellulose derivatives, said solution being unsaturated With respect to the salt to be removed.

13. Process for the treatment of materials con- ,taining organic derivatives of cellulose which contain soluble salts, so as to remove said salts without delustering, comprising treating said materials with an aqueous solution of a substance selected from the group consisting of organic sol,- vents and swelling agents for the organic derivative of cellulose WILLIAM ALEXANDER DICKIE. PERCY FREDERICK COMBE SOWTER. 

